Indicator for electrically-driven clocks



H. E. WARREN. INDICATOR FOR ELECTRICALLY DRIVEN CLOCKS.

APPLICATION FILED m4. 4,1911.

1;334,423. I I I Patented Mar. 23, 1920.

l/VVE-NTOK.

v UNITED STATES PATENT o TEIoE.

' HE RY E. WARREN, 0F ASHLAND, MASSACHUSETTS, AssIcNcR 'ro WARREN cLocK- COMPANY, or ASHLAND, MAssacHUsE'r'rs, A CORPORATION or MAINE.

INDIcA'roRInoR.EL oTRIcALLY-nRIvnN CLOCKS.

To all toho-m it may concern:

die it known that I, HENRY E. WARREN, a citizen of theUnited States, anda resident of Ashland, in the county of Middlesex and Stateof Massachusetts, have invented an Improvement in Indicators 'for Electrically-Driven Clocks, of which the following, description, in connection with'the accom-- panying drawings, is a specification, like characters on the. drawings representing like parts. r

My invention relates to indicators forelectrically driven instruments having a timing I function and has for its object the provision of a simple and reliable indicating device for indicating whether the current supplied to drive the instrument has been interrupted sufficiently long to vitiate the timing function discharged by such instrument.

My invention is particularly adapted to be used in connection with clocks which give time indications and are dependent on some I characteristic of the current supplied; for instance, where the clocks are driven by synchronous motors, the time keeping qualities of which are dependent on the freedom from interruption of the alternating current supplied.

In carrying out my invention in its present form, I have app-lied it to the type of electrically driven clock shown in Patent No. 1,283,431 issued in my name on October 29, 1918, and have employed a device which is normally concealed from view while the clock is running under normal or substantially normal conditions, but which becomes .visibleunder abnormal conditions and is proportioned to remain visible at the will of the operator and independently of the cur rent flowing through a reestablished circuit if the current interruption exceeds in duration a predetermined time interval, whereby the operator has his attention called to the fact, thatthe clock if running with the in dicator displayed is indicating inaccurate time and should be reset.

These and other features of this invention will be pointed out in the claims at the end of this specification.

Figure 1 is a front view of a portion of an electrically operated clock provided with one form of indicating device embodying this invention in the position it occupies when the clock is operating under normal 3 conditions.

Specification of Letters Patent.

Patented Mar. 23, 1920.

Application filed January 4, 1917. Serial No. 140,526.

electrically driven clock, which may be of any suitable or desired construction, and 18 preferably substantially constructed as shown and described in the patent above referred to; In the present instance, I have deemed it unnecessary to show more than a sufficient part of the clock to .enable the application of my present invention to be understood, and therefore I have illustrated an alternating current synchronous motor I) provided with the stator c which is excited by the alternating current supplied for driv-. ing the clock mechanism represented in Fig. 3 by the gears d.

In accordance with the present invention, the clock a is providedwith an indicating device which is normally under the influence of the magnetic field of the stator c and remains under control of such field, as long as the current is flowing through the coil 10 on the stator 0, or so long asthe flow of current is interrupted only momentarily or for substantially short periods of time, as, for instance, an interruption which does not lastinduration more than one or two seconds. This device is also preferably so located that it moves out of the influence of the magnetic field when the interruption exceeds in duration such predetermined in terval of time.

In the present instance this indicating device is shown as comprising a visual indicator in the form of a drop plate or tablet 12 attached to a lever 13 which is fulcrumed at 14. This lever is here represented as a wire rod made of magnetizable material such as soft iron; the wire being conveniently coiled to embrace the pivoted pin at 14 to form the fulcrum. The tablet or drop plate 12 is attached to the arm of the lever denoted 15, while the pendent arm 16 is disposed somewhat at an angle to the arm 15. Thus with a slight movement of the lever 13 the tablet ordrop plate 12 is moved "to and from behind a convenient portion of the casing 17 of the clock so as to be concealed from view, when the arm 16 is under the infiuence-.- of the stator 0, and in substantially the po- I indicator,

sition shown in Fig. 1, and that the dro or tablet 12 is brought into view in front 0 the dial 18 of-the clock, when the arm 16 is moved out of the influence of the magnet and into substantially the position shown in Fi 2. I The arm 16 is preferably arrested in its movement toward the stator oby a suitable stop or pin 19, and is moved away from said stator by suitable means, such as its own weight partially balanced by a counterweight 20 on an arm 21 attached to the lever 13. The stop 19 is preferably located so as to arrest the arm 16 in a position to leave-a small air gap 22 between the arm and the stator a, and thus prevent an annoying humming sound which might occur on account of the alternating current employed if the arm 16 came in contact with the mag net 0. The lever having the indicating device is suitably pivoted so as to be able to swing very easily. r

The operation of the indicating device herein shown may be briefly described as follows :Assume that the current is flowing through the circuit in which the field coil 10 in the stator of the motor 6 is included, and that the clock has been set to indicate accurate time, and further that the operator has moved the arm 16 over against the stop 19, so that its free end is within the influence of the magnetic field of the stator c. In this case, the drop plate 12 which bears the word reset as herein shown, is

moved behind the clock case 17 and into the position shown in Fig. 1, and remains in this position as long as the current is not interrupted for a material length of time, that is, while the current is wholly uninterrupted or interrupted for only such short periods of time as do not exceed in duration that determined by the proportions of arm 16.

In this latter case, the arm 16 and the other parts of the indicator will oscillate like a pendulum upon the pivot '14, and willnot, within this short interval, come completely to rest in the reset or permanent position shown in Fig. 2, since before such oscillations die out, the field of the stator a will again be restored to attract the arm 16 and hold it in the position shown in Fig. 1 by the reestablishment of the current with in the predetermined period. This requires the placing of arm 16 so that its lower end during the gradually diminishing oscillations shall approach rather closely to the stator in order to be within the influence of the latter during the predetermined period.

the current/,yfails for; a.

When, however, longer time interval, say six or eightgseconds,.the arm 16' and the remainder ,of the swinging, as to have reached the permarient positiomshown in Fig. 2, hence the will have so nearly stopped" magnetic attraction of the stator 0 when the current is restored, will not be suiticient to move the arm 16 from its position of rest shown in Fig.2. The indicator or drop plate 12 consequently will remain below the upper part of the clock casing 17 where it partially covers some of the-figures on the dial 18 and indicates in the clearest possible manner that the clock is not normal and should be reset.

By merely touching it with the fingers, the indicator or drop plate 12 can be moved back to its normal position at the same time that the hands of the clock are set, and the indicator, will then be on guard until the occurrence of the next interruption of the current of sufficient duration to bring about its reappearance on the face of the dial.

The position. occupied by the indicator under normal condition is shown in Fig. 1 and may be termed its inoperative position, and that shown in Fig. 2, its operative position. Furthermore, the indicator herein shown constitutes a visual signal to notify the operator that the clock should be reset, but it is not desired to limit the invention in this respect, as an audible signal operated by movement of thearm 15 may be used instead.

While I have shown my invention as incorporated in the structure of a clock, which has been chosen for purposes of illustration as the instrument having a timing function, obviously my invention is not so limited, but may be applied anywhere to the 100 energy supplying circuit of the electrically driven instrument.

So also one embodimcntof the invention is herein shown, but it is not desired to limit the invention in this respect, as it is obvious 105 thatthe device herein shown may be modifled in various ways without interfering vwith its general utility or. departing from the invention herein disclosed.

Claims:

The combination with an instrument havii'ifga't'iming function driven by an electric motongofa device under. the influence of current supplied to said motor while ---nating current synchronous motor, of a magnetic device cooperating with said motor for the purposeof shovvingthat the clock is not correct after there has been an interruption of a predetermined length of time in the current supplied to the motor.

4. The combination With an instrument having a timing function driven by an electric motor, of a device normally inactive while the motor is uninterruptedly supplied with current and becoming active to indicate a failure of the current in response to an interruption of the current Without. influencing the continuity of flow of said current.

5. The combination With an electric circuit,-of an electrically operated device for indicating interruptions of the current in said circuit, said device being constructed and arranged to be non-responsive as a perm anent indication to short interruptions but responsive as a permanent indication to relatively long interruptions of the current and unin ciuencedv as a permanent indication by reestablishment of the circuit until the indicating device has been reset into its normal position. r

6. The combination with a clock, of an electric motor for driving the same and a movable indicating device carried by the clock and cooperating with said motor to be maintained in one condition While the electric current supplied to the motor is maintained and to be moved into another condition upon interruptions of the current, said device being responsive to the reestablishment of the current after a momentary interruption to be restored to the first-mentioned condition and non-responsive to the reestablishment of the current after a prolonged interruption.

7 The combination With an electrically driven clock, of an indicating device adapted to be moved to a position to indicate that the clock has been stopped by failure of curmeans being proportioned and arranged to 'cause said indicating device to give a pen manent indication only in response to a fail- I ure of said current which exceeds in duration a predetermined time.

9. The combination With an electrically driven clock, of an indicating device adapted to be moved into a position to indicate that the clock has been stopped by failure of current, and means comprising an arm having a pendulum action controlled by the current supplied to drive said clock for actuating said indicating device.

10. In an instrument, the combination With a time indicating element, of a synchronous alternating current motor for driving said element, and indicating means under the control of the current supplied to said motor; said means provided with an arm having a pendulum'action so proportioned as to give a permanent indication only in response to a cessation in said current Which does exceed in duration a predetermined interval of time and so disposed in the field of influence of said current as to be unresponsive to a reestablishment thereof after a permanent indication has been given.

In testimony whereof, I have signed my name to this specificatlon.

HENRY E. WARREN. 

